<html>
    <head>
      <base href="http://llvm.org/bugs/" />
    </head>
    <body><table border="1" cellspacing="0" cellpadding="8">
        <tr>
          <th>Bug ID</th>
          <td><a class="bz_bug_link 
          bz_status_NEW "
   title="NEW --- - clang crashes on valid code at -O1 and above on x86_64-linux-gnu"
   href="http://llvm.org/bugs/show_bug.cgi?id=18083">18083</a>
          </td>
        </tr>

        <tr>
          <th>Summary</th>
          <td>clang crashes on valid code at -O1 and above on x86_64-linux-gnu
          </td>
        </tr>

        <tr>
          <th>Product</th>
          <td>clang
          </td>
        </tr>

        <tr>
          <th>Version</th>
          <td>trunk
          </td>
        </tr>

        <tr>
          <th>Hardware</th>
          <td>PC
          </td>
        </tr>

        <tr>
          <th>OS</th>
          <td>All
          </td>
        </tr>

        <tr>
          <th>Status</th>
          <td>NEW
          </td>
        </tr>

        <tr>
          <th>Severity</th>
          <td>normal
          </td>
        </tr>

        <tr>
          <th>Priority</th>
          <td>P
          </td>
        </tr>

        <tr>
          <th>Component</th>
          <td>-New Bugs
          </td>
        </tr>

        <tr>
          <th>Assignee</th>
          <td>unassignedclangbugs@nondot.org
          </td>
        </tr>

        <tr>
          <th>Reporter</th>
          <td>su@cs.ucdavis.edu
          </td>
        </tr>

        <tr>
          <th>CC</th>
          <td>llvmbugs@cs.uiuc.edu
          </td>
        </tr>

        <tr>
          <th>Classification</th>
          <td>Unclassified
          </td>
        </tr></table>
      <p>
        <div>
        <pre>The current clang trunk crashes when compiling the following testcase at -O1
and above on x86_64-linux-gnu in both 32-bit and 64-bit modes. 

This is a regression from clang 3.3.


$ clang-trunk -v
clang version 3.5 (trunk 195916)
Target: x86_64-unknown-linux-gnu
Thread model: posix
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.4
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.4.6
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.4.7
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.6
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.6.3
Selected GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.6

$ clang-trunk -O0 -c small.c 
$ clang-3.3 -O1 -c small.c
$  
$ clang-trunk -O1 -c small.c
0  clang           0x00000000021c7e65 llvm::sys::PrintStackTrace(_IO_FILE*) +
37
1  clang           0x00000000021c82a3
2  libpthread.so.0 0x00007f29e7c2fcb0
Stack dump:
0.    Program arguments: /usr/local/clang-trunk/bin/clang -cc1 -triple
x86_64-unknown-linux-gnu -emit-obj -disable-free -main-file-name small.c
-mrelocation-model static -fmath-errno -masm-verbose -mconstructor-aliases
-munwind-tables -target-cpu x86-64 -target-linker-version 2.22
-momit-leaf-frame-pointer -coverage-file
/data2/c-hunter-results/C/trans-bugs/20131128-clang-m32-m64-O1-O2-O3-Os-build-test790089/small.o
-resource-dir /usr/local/clang-trunk/bin/../lib/clang/3.5 -internal-isystem
/usr/local/include -internal-isystem
/usr/local/clang-trunk/bin/../lib/clang/3.5/include -internal-externc-isystem
/usr/include/x86_64-linux-gnu -internal-externc-isystem /include
-internal-externc-isystem /usr/include -O1 -fdebug-compilation-dir
/data2/c-hunter-results/C/trans-bugs/20131128-clang-m32-m64-O1-O2-O3-Os-build-test790089
-ferror-limit 19 -fmessage-length 103 -mstackrealign -fobjc-runtime=gcc
-fdiagnostics-show-option -fcolor-diagnostics -vectorize-slp -o small.o -x c
small.c 
1.    <eof> parser at end of file
2.    Per-module optimization passes
3.    Running pass 'Global Variable Optimizer' on module 'small.c'.
clang: error: unable to execute command: Segmentation fault (core dumped)
clang: error: clang frontend command failed due to signal (use -v to see
invocation)
clang version 3.5 (trunk 195916)
Target: x86_64-unknown-linux-gnu
Thread model: posix
clang: note: diagnostic msg: PLEASE submit a bug report to
<a href="http://llvm.org/bugs/">http://llvm.org/bugs/</a> and include the crash backtrace, preprocessed source, and
associated run script.
clang: note: diagnostic msg: 
********************

PLEASE ATTACH THE FOLLOWING FILES TO THE BUG REPORT:
Preprocessed source(s) and associated run script(s) are located at:
clang: note: diagnostic msg: /tmp/small-e7903c.c
clang: note: diagnostic msg: /tmp/small-e7903c.sh
clang: note: diagnostic msg: 

********************



--------------------------------------


static char a[2][1];
static char *b[2] = {&a[1][0], &a[0][0]};
static char **c = &b[1];

void
foo ()
{
  **c = 0;
}</pre>
        </div>
      </p>
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